Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2010
Abstract
One of the main challenges for new wood protection systems is to predict in a fast and accurate way service life in use class 3 (above ground) and use class 4 (in soil or fresh water contact). New environmentally benign wood protection systems are expected to have different modes of action against wood deteriorating fungi compared to the traditional preservatives, change in water sorption being one of them. Therefore it is of importance to evaluate new treated wood products in a broad range of exposure situations, also exploring the variation within use class 3 and 4. Due to the restrictions in the use of chromium containing wood preservatives, a range of studies have been published the last decade evaluating the performance of new products after laboratory or field test exposure. However, there is still a lack of studies comparing the same material in different field exposure situations. This study evaluates the efficacy of 13 novel wood protecting systems in three different above ground tests (horizontal double layer, block test and mini stakes) and two different in-ground tests (EN 252 and mini stakes). Scots pine (Pinus sylvestris L.) sapwood from the same wood source was used for all treatments. For each wood protecting system the wood specimens for all five tests were treated together in the same batch. The results after five years of field exposure are presented. In the three above ground tests no or only initial signs of decay were detected after five years (not reaching a mean rating of 1). The decay rate in soil contact was faster than above ground, but after five years only untreated wood (controls) failed in both tests. No significant difference in performance was found between the two tests in soil contact. The use of median decay rate values gave an earlier indication of performance than the use of mean decay rate values.
Abstract
Modified wood can provide protection against a range of wood deteriorating organisms. But we still lack information about why the modified wood is protected from microbial attack. Several hypotheses have been put forward for the mode of action against wood decaying fungi, including inhibition of action of specific enzymes, but they still need further testing. In this study gene expression of the brown rot fungus Postia placenta FPRL 280 has been monitored after 2, 4 and 8 weeks of colonization in furfurylated Scots pine (Pinus sylvestris L.) and in untreated control samples. Preliminary results are given. The main finding was that genes related to oxidative metabolic activity generally was higher in furfurylated wood compared to untreated Scots pine. Carbohydrate metabolism related expression varied. For one endo-glucanase and two β-glucosidases the expression was lower in furfurylated wood compared to untreated control, while for one glucoamylase and one glucan 1,3b glucosidase the expression was higher in furfurylated wood. The four cytochrome P450 tested, involved in breakdown of toxic compounds, gave inconsistent results between furfurylated and untreated control samples. Phenylalanine ammonia lyase and cytosolic oxaloacetase gave higher expression in control than in furfurylated samples.
Abstract
Scots pine (Pinus sylvestris) sapwood is per definition (EN-350-2) easy to treat. Combination with its good availability on the European markets, it is a construction and building material in demand. However, partially large differences in penetration are reported from industry and research. To keep a reliable product quality, impregnation processes aligned to the material most difficult to treat. Hence, it is crucial to know about the factors inhibiting the fluid flow into the material. Scots pine samples from a wide geographic distribution, 25 different sites in 6 different countries, have been collected and impregnated with an aqueous monomer furfuryl alcohol solution. From each of the respective sites logs of 1.3 meter in length were collected from nine trees belonging to three different breast height diameter classes. Three trees from each dominance class were chosen randomly. The log was drawn from the felled stem in a height of 1.2 meters with exact marked north/south exposition. Sapwood slabs orientated in the heaven directions, underwent a drying procedure at 40°C for 48 h and small clear samples of 20 x 20 x 50 mm were prepared. A large variation of the ratio of filling was found for the material tested. Diameter as well as sample origin seem to influence the materials permeability.
Abstract
Development in surface mould growth on painted/unpainted wooden claddings and acting climatic factors were investigated over a period of 3 years. Eight wood substrates, including modified, preservative-treated and untreated wood, were tested in combination with three types of paint: (1) water-borne alkyd modified acrylic paint without fungicide; (2) solvent-borne alkyd paint without fungicide; and (3) ICP (internal comparison product). One set of samples was exposed unpainted. The samples were tested according to a modified version of EN 927-3. A logistic regression model was fitted to the data. The degree of mould growth varied with exposure time, coating typology, wood substrate, temperature and relative humidity. Exposure time and coating typology contributed most to the model. After 3 years of outdoor exposure unpainted panels and panels coated with solvent-borne paint without fungicide had more mould growth than panels coated with ICP and water-borne paint without fungicide. Unpainted oil/copper–organic preservative-treated claddings had higher resistance to mould growth than other unpainted wood substrates. Coated untreated pine and coated acetylated pine were more susceptible to mould growth than other coated wooden substrates.
Abstract
Microbial disfigurement of coated wooden surfaces is considered a major maintenance concern and will shorten the aesthetic service life of wooden facades. The effect of the physical surface structure of a paint film when applied on wood may have an impact on the susceptibility to mould growth. Six model paints were formulated to give the following physical surface structures: glossy, matt, soft, hard, hydrophobic, and a film with air inclusion. The model paints and a standard paint, with and without fungicide, were applied on panels of Norway spruce (Picea abies L Karst.) and exposed outdoors for nearly three years according to a modified version of EN 927-3. A logistic regression model was fit to the data, and the degree of mould growth varied with exposure time and type of paint. Hard model paint was significantly more susceptible than the other model paints and had a performance close to the standard paint without fungicide. Soft model paint provided the best performance, with the least mould growth. Temperature, relative humidity, and precipitation did not significantly contribute to the model. (C) 2010 Elsevier Ltd. All rights reserved.
Authors
Per Otto Flæte Gry Alfredsen Kristian Bysheim Øyvind Eriksen Anders Qvale Nyrud Birger VenneslandAbstract
Roundwood timber is raw material for numerous products. Wood based products are generally recognised as favourable regarding energy consumption and greenhouse gas (GHG) emissions. Several studies have shown that the net CO2 emissions can be reduced by using biofuels harvested from forests to substitute fossil fuels, and by using wood for building materials. Energy use and GHG emissions associated with producing roundwood can be influenced by a broad range of factors, such as silvicultural practice, topography, applied technology, forestland ownership, industrial structure, etc. This emphasizes the importance of using representative data for energy use and GHG emissions when calculating environmental impacts. The aim of this study was to investigate the embodied energy and life cycle GHG emissions of industrial softwood sawlogs in Norway, covering the production chain from tree seed to log yard. Analyses were based on activity data for the Norwegian forest sector for the year 2007. The results showed that the embodied energy and GHG emissions were low compared with the energy and CO2-equivalents stored in the roundwood (about 2%). The findings from this study can be used to inform future decisions on processes in forestry that should be focused on when planning actions to reduce energy consumption and GHG emissions. Additionally, as roundwood timber is raw material for numerous products the results can be useful when preparing documentation of environmental impacts, such as environmental product declarations, which are increasingly demanded by the market.
Abstract
Traditional wood preservatives based on biocides are effective against wood-deteriorating organisms because of their toxicity. By contrast, modified woods are non-toxic by definition. To investigate the efficiency of various wood modifications, quantitative real-time polymerase chain reaction (qPCR) was used to profile the DNA amounts of the white-rot fungus Trametes versicolor (L.) [Lloyd strain CTB 863 A] during an 8-week-long growth period in treated Pinus sylvestris (L.) sapwood. The studied wood was modified by acetylation, furfurylation, and thermal treatment. The traditional wood preservatives bis-(N-cyclohexyldiazeniumdioxy)-copper (Cu-HDO) and chromated copper arsenate (CCA) were used as references, whereas untreated P. sylvestris (L.) sapwood served as a control. The maximum levels of fungal DNA in native wood occurred at the end of the experiment. For all wood treatments, the maximum fungal DNA level was recorded after an incubation period of 2 weeks, followed by a decline until the end of the trial. For the preservative-treated woods, Cu-HDO showed the lowest level of fungal DNA throughout the experiment, indicating that exploratory hyphal growth is limited owing to the phytotoxicity of the treatment. The other treatments did not inhibit the exploratory hyphal growth phase. We conclude that qPCR studies of hyphal growth patterns within wood should provide a powerful tool for evaluating and further optimizing new wood protection systems.
2009
Abstract
New environmental benign wood protection agents often come from natural resources, and are sometimes a waste product. Chitosan, a derivative from chitin which is among other sources a by-product from the shellfish industry, is tested as well as known wood protection agents and their synergetic effect with chitosan. The objective of the research presented in this paper, is to describe the leaching properties of the following compounds: Chitosan, chitosan/copper, chitosan/boron and chitosan/ScanImp (a commercial wood preservative). A leaching procedure was performed on treated Scots pine sapwood samples. The four solutions have also been tested with and without post treatment. A new effective fire preservative has been included in the test. Common wood preservatives have been tested as references. The combination with chitosan did improve the fixation of the wood protection agent ScanImp. Furthermore, the post treatment of the chitosan treated samples did significantly reduce the leaching of glucosamine and to some extend also the leaching of boron.
Abstract
The durability of wood in exterior use is limited by to climatic factors and wood deteriorating organisms. The natural durability of the Nordic wood species is generally regarded as low, and for e.g. decking and use in soil contact wood protection is needed. Within the last years, new non-biocidal treatments, like wood modification systems, have been developed to improve the biological resistance of wood. For information about the decay resistance of untreated and modified wood, natural outside exposure is necessary. European standard EN 252 is the main field test method for use class 4. In use class 3 the need of new or improved test setups has been put forward. Traditionally evaluation of field trials has mainly been based on visual evaluation and pick-test. However, to get in depth knowledge about: 1) different field trial methods and 2) fungal colonization of new wood protection systems, additional assessment methods can be used. Hence, comparative studies are needed.....
Abstract
One of the biggest drawbacks of using European native wood species as a construction material is its tendency to degrade by fungal attack. This has lead to the development of different systems for wood preservation. Many of these systems suffer the disadvantage that they contain biocides, which can leach from the wood into the environment and damage organisms. In this project ten silanes, 3-(2-Aminoethylamino)propyltrimethoxysilane, 3-[2-(2- aminoethylamino)ethylamino]propyltrimethoxysilane, 3-Aminopropyltrimethoxysilane, Diethoxydimethylsilane, Dodecyltriethoxysilane, Hexadecyltrimethoxysilane, NTrimethoxysilylpropyl- N,N,N-trimethylammoniumchloride, Octyltriethoxysilane, Octyltrimethoxysilane and Phenyltrimethoxysilane, have been investigated for their ability to increase the hydrophobicity of wood and decrease shrinking and swelling, and thus increase its ability to withstand attack by fungi. In the initial phase of the project two solvents, ethanol and water were investigated to find out which of these that gave the best result for surface modification with silanes. The results showed that water as solvent gave a surface with higher hydrofobicity than when ethanol was used as solvent....